A communication was made to this Society on February 3, 1902, on ‘Magnetic Shielding in ollow Iron Cylinders.’ At an early stage of this investigation, and when dealing with more magnetising forces than that due to the transverse field acting upon the shield, the subject of cross magnetisation necessarily came to the front. This paper deals, First, with the superposition of two magnetising forces at right angles to each other, and the coordination of the two components of the resultant magnetic induction, under the various conditions of field superposition; and Second, with the magnetic œolotropy of demagnetised iron. The same hollow iron cylinders were used as in the shielding experiments.